Potassium content in natural bodies of water is far lower than that of sodium. Its concentration is usually only 4% to 10% of that of sodium. In some quartzite areas, the potassium content in natural water is near or exceeds sodium content but both of them are very low, only some single-digit mg/L respectively. In most fresh water with sodium concentration below 10mg/L, the potassium concentration is only 10% to 50% of the sodium concentration. In some alkaline water or hot springs, the potassium concentration multiplies by orders of magnitude. In brine, the potassium concentration is ten mg/L to hundreds of mg/L. Furthermore, potassium is a basic nutrient of plants and is absorbed by plants during the weathering process.